Genotypic Selection is a novel form of selection postulated to exist at the intracellular level and acting directly on nucleic acids before their expression. It addresses itself to the questions of 'How does DNA use its information for its own survival?' and 'What are the constraints and restraints on allowable DNA sequences in nature?'. In my original grant, I proposed to approach this question by directly sequencing a simple viral DNA and developing computer algorithms, programs, and language to handle large nucleotide sequences for secondary structure, pattern recognition, homology, and quasi-homologies. In this grant renewal I wish to extend these studies with an experimental tool which extends and clarifies the concept and perspective of Genotypic Selection. I call this experimental approach Genotypic Mapping. Genotypic Mapping is analogous to classical genetic mapping except that it maps non-expressed regions rather than expressed function. The conceptual distinction is important as genetics, almost by definition, requires mapping of expression and viability of progeny. Genotypic mapping will map the non-essential regions of a viral DNA. These regions will be mapped to the nucleotide level and in such a manner that regions between non-essential regions, i.e. function regions, can be isolated. Sequences of DNA can be mapped as to structure, syntax, and function without knowing or needing to know the protein or RNA product. It requires a simple and logical extension of the sequencing methodology we are presently employing.